1. Field
The field of the invention is electrical signal transmission cable assemblies for use with audio speakers.
2. State of the Art
Some flexible cable assemblies include multiple electrical conductors. U.S. Pat. No. 4,675,474 discloses parallel or twisted, heavily insulated pump power transmission conductors potted together in a filler material in turn encased in a protective armor covering. The assembly is vulcanized to stabilize the filler material. The resulting assembly has little flexibility, and no capability for providing continuous signal transmission without distortion. The assembly appears to rely upon spirally wrapped, non-conducting, filaments for strength, in cooperation with a tape winding of polypropylene, nylon or the like, and essentially comprises a tube, completely filled with solidified material. The sharp bends needed for speaker cables could not be accommodated. A similar assembly is disclosed in U.S. Pat. No. 3,140,087, wherein the conductors are braided along with non-elastic reinforcing fibers about a solid core of elastic rubberoid material. This assembly is encased in two layers of similar material, so that the bending flexibility is quite limited. The objective of this disclosed assembly is to provide stretchability to the cable without damage to the conductors. The braided non-elastic fiber provides stretch maintained within limits by tightening of the braid about the core. The conductors, braided along with the non-elastic fibers, are protected from damage. The degree of flexibility needed for speaker cables is not provided. No stabilization of conductor position is provided, as needed for fidelity in speaker signal transmission. U.S. Pat. No. 1,305,247 discloses an electrical lead wire assembly having two conductors spirally wound about a core. This subassembly is covered by an elastomeric sheath. The core may be hollow for increased flexibility. No opposite spiralling of the conductors is disclosed. Neither this cable nor any other of the disclosed cables, nor any known speaker cable design, provides enough mass and weight to effectively stabilize the cable from internally induced mechanical vibration by magnetic field interaction, or from air and structure borne vibration from the loudspeaker while it is playing.
A need therefore remains for providing a speaker cable assembly that may be installed in sharply flexed but stable position during operation. Also needed is such an assembly particularly adapted to reduce or eliminate spurious noise and signals from conductor magnetic fields, as well as from external sources.